This invention relates to handling of building panels at construction sites and more particularly to equipment for transporting and lifting of panels to an elevated position convenient to installers.
Handling of building panels such as drywall or xe2x80x9cSheetrockxe2x80x9d panels has presented difficulties, especially for large panels being installed in commercial buildings at heights above a first floor level. Drywall panels for such applications may be as large as four feet by twelve feet and weigh one hundred pounds or more. It is readily apparent that any improvements in equipment and procedures for lifting such panels to a required elevated location would be welcomed by installers.
Use of scissors-type lift machines has become a common practice at commercial building sites. These devices have sets of paired extendable arms mounted on a wheeled and powered chassis and a work platform supported by the arms. For safety reasons the platforms include horizontal rails around their outer edges supported by upright posts. The rail structure generally includes an upper rail some three feet above the platform floor and a lower rail halfway between the floor and upper rail. The rails generally take the form of square metal tubing. Lift platforms may be eight feet by three feet and provide space for two to three workmen. Machines of this type are exemplified by U.S. Pat. No. 6,158,550, issued Dec. 12, 2000 to Arnoldy, which patent is hereby expressly incorporated by reference.
Attempts have been made to use existing lift devices for lifting large panels along with the workmen to an elevated working level, but various disadvantages are presented. If the panel is longer than the platform it could only be carried on top of or outside of the rails, which would be difficult or even unsafe to the workers. Also the panel might end up in a position requiring awkward moves by the workman to place the panel in final location. In addition, operations such as sliding a panel over a platform or rail might result in damage to the panel.
The present invention is directed to apparatus for lifting and transporting panels of material such as drywall to a desired location at a construction site. The apparatus comprises a pair of panel-receiving legs attachable to horizontal side rails of a lift platform, with the legs when attached extending generally in a vertical direction. Square metal tubing is a suitable material for making the legs.
Each of the legs has a top, bottom and midpoint along its length, an inside surface facing the platform from the outside when installed and an outside surface facing the opposite direction. Clamps for making connection to upper and lower rails of a lift platform may be removably attached to the rail on the inside of the legs, an upper clamp at the top of the leg and a lower clamp at a midpoint. The legs have a panel-receiving channel provided at the bottom of the leg and on the outside thereof. A low friction contact member at base of the channel is used to obtain enhanced rolling or sliding movement of panels, and a horizontal guide serves to return the panels in position.
Low friction contact surfaces may also be provided at various other locations so as to keep the panels from being slid over the surfaces which present higher friction. This feature may be implemented in the form of rollers located at the base of the channel at the top of the leg, at a side or the channel above the base roller and at a midpoint of the leg. In each case the roller is placed so that its circumference extends to provide space away from surfaces of other structural members.
To provide for easier handling of panels and to keep them from falling out of the channel, the leg may be adapted for being inclined outward at the bottom at an acute angle such as ten to fifteen degrees from the vertical. This result may be obtained by mounting the lower clamp on a standoff member at a suitable length whereby the bottom of the leg is projected outward.
Variations in the distance between upper and lower rails of different platform lifts may be accommodated by pivotally mounting the lower clamp support on the leg and by providing a series of vertically separated holes through the leg to allow for adjustment by insertion of a pin in a selected mounting hole. Use of the apparatus for narrower panels having a width such as two foot may be enabled by placement of the channel structure at a midpoint of the legs. For this purpose this component may be removably mounted for attachment at the midpoint as well as at the bottom of the leg.
Another desirable feature of the invention is to provide a braking mechanism for the roller at the base of the channel to prevent unintended rolling or sliding when the platform is moved. Locking of the load-bearing wheel at the base of the channel, as by insertion of a pin, may be employed.
Apparatus embodying the invention provides important advantages, particularly in the ease and convenience of moving large and heavy panels to a position which is optimum for further movement into the final location for installation. Safety and productivity of panel installers are thereby enhanced, and damage to panels is reduced.
It is accordingly an object of this invention to provide a panel-carrying attachment for lift platforms.
Another object is to provide a panel-carrying attachment having low friction, load-bearing surfaces enabling ease of loading.